The present invention relates to magnetostatic wave delay lines and in particular to means for improving the linearity of group delay versus frequency in such devices. Magnetostatic waves are periodic disturbances of the magnetization which can propagate, for example, in a film of a magnetic garnet crystal such as Yttrium Iron Garnet (YIG). They are the magnetic analog of acoustic waves in crystals. As such they offer the potential for device application as delay lines in the processing of radar signals at microwave frequencies with the additional advantage of lower insertion loss over their acoustic counterparts. In particular their inherently dispersive behavior offers the potential for pulse compression filtering in ECM applications at L- and S-bands such as the microscan receiver. They would also operate at least up to X-band. The group delay versus frequency characteristic for these waves have been made approximately linear over a certain frequency range by placing the YIG film an appropriate distance from an electrical ground plane. Further improvement, however, in linearity of group delay is desirable for many applications. It is also an object in magnetostatic delay line design to achieve group delay linearity over an extended frequency range. These requirements cannot be met fully by state-of-the-art techniques. Accordingly, there currently exists the need for magnetostatic delay lines having improved group delay linearity versus frequency over extended frequency ranges. The present invention is directed toward satisfying that need.